[c-nsp] iphone, Cisco AP/WLC & web-auth

[Yuri Lukin]

On Thu, 02 Aug 2007 12:19:28 -0700, matthew zeier wrote
> Yuri Lukin wrote:
> 
> > When the iphone sleeps, does it go into Power Save Mode?
> 
> I don't know and I don't know how to check (the screen goes dark). 
>  If it did, and powered the radio off, would that matter?

Yes, if the iphone goes into power save mode, the radio will power off to
conserve battery power and it will wake up periodically and poll the AP with a
PS Poll frame to see if there are any packets buffered for it. If there's a
delay in the "wake-up mechanism", the AP may ignore the PSP frames and thus
cause the iphone to re-auth. This is a common problem with many hand-held
devices using power save mode, that's why sometimes it can help if you disable
it on the client. You can confirm if this is indeed the case by running a
wireless sniffer like Airopeek or Omnipeek Personal.